Scores on a Particular Test Have a Mean of 64

Multiple Choice

Scores on a particular test have a mean of 64.6 and a standard deviation of 15.0. Suppose you take a sample of size 100 of test scores and find that the mean is 63.1. What is the z-score corresponding to this sample mean?

A) 1.5
B) ?1.5
C) ?0.1
D) ?1.0